Question

An electron beam is moving vertically upwards. If it passes through a magnetic field which is directed from South to north in a horizontal plane, then in which direction will the beam deflect?

Answer 1

Using the right-hand rule, and reversing it due to the electron's negative charge, the electron beam passing through a magnetic field from South to North would deflect to the East.

Step-by-step explanation:

The direction of the deflection of an electron beam moving vertically upwards when it passes through a magnetic field directed from South to North in a horizontal plane can be determined using the right-hand rule. Since electrons have a negative charge, you would use your left hand for prediction, but since the question specifies an electron, we will reverse the direction given by the standard right-hand rule.

Place your thumb in the direction of the electron velocity (upwards), and your fingers in the direction of the magnetic field (from South to North). Your palm now faces the direction of the force on a positive charge, but since electrons are negatively charged, the force will be in the opposite direction. Therefore, the electron beam will deflect to the East.